The invention described herein may be manufactured and used by or for the Government of the United States for all governmental purposes without the payment of any royalty.
This invention relates to the field of small mechanical metallic electrical switches, i.e., micromechanical electrical switches (MEMS) of the type usable for low loss switching in a radio frequency integrated circuit device.
In view of the signal power losses and often encountered with the use of semiconductor switch devices in electronic systems operated in the microwave and gigahertz spectral regions (i.e., losses occurring in both the open and closed switch conditions) it is often desirable to resort to simple mechanical switching devices to accomplish signal path changes in such systems. This election is frequently complicated, however, by the need to accomplish such switching within the package of an integrated circuit device and in an environment wherein signals are communicated along paths comprising an electrical transmission line. Further complications arise from the often high operating speed combined with need for a long operating life from such switches and from the need to employ switch fabrication materials compatible with the processing steps and the specific materials used during wafer fabrication for an integrated circuit device. The actuation mechanism for such switching devices gives rise to additional areas of concern since clearly the magnetic actuation arrangements frequently used in other switching environments is all but unavailable in the limited space and limited materials environments of an integrated circuit device.
The present invention is believed to offer a mechanical switching device of the MEMS i.e., micromechanical electrical systems type, a basic single pole single throw switch accommodating several of these complications, providing low switch input to output stray coupling and advancing the art of MEMS integrated circuit switching to a new level.
The present invention provides a die mounted externally controllable microminiature electrically energized electrical switch or relay usable in the circuitry of an integrated circuit die, and mounted within the integrated circuit package, for circuit path change purposes.
It is an object of the present invention, therefore, to provide an integrated circuit-compatible metallic electrical switch.
It is another object of the present invention to provide an integrated circuit-compatible metallic electrical switch of the single pole single throw type.
It is an object of the present invention to provide an integrated circuit-compatible metallic electrical switch of the shunted single pole single throw type.
It is an object of the present invention to provide an integrated circuit-compatible metallic electrical switch having one switch node selectably connectable with either a switch output node or a signal grounding shunt.
It is an object of the present invention to provide an integrated circuit-compatible metallic electrical switch of the single pole single throw and either normally open or normally closed type.
It is another object of the invention to provide an electrically controllable electrical switch, a switch having certain attributes of an electrical relay.
It is another object of the invention to provide an electrical switch compatible with the components and processes used in an integrated circuit device.
It is another object of the invention to provide an electrical switch well suited to the switching of radio frequency electrical energy in an integrated circuit die.
It is another object of the invention to provide an electrical switch especially suited for use in an integrated circuit electrical transmission line environment.
It is another object of the invention to provide an electrical switch employing capacitance coupling connection between input and output electrodes of the closed switch.
It is another object of the invention to provide an electrical switch having movable and plural fixed metallic members, members all formable with integrated circuit processing techniques.
It is another object of the invention to provide an electrical switch having a movable member physically restrained in each of its open and closed operating positions.
It is another object of the invention to provide an integrated circuit electromechanical switch having a physical component operating life measured in the ten to the ninth power and greater range.
It is another object of the invention to provide a metallic element electrical switch having operating cycle times measured in the range of microseconds.
It is another object of the invention to provide an electrical switch in which capacitance coupling through the electrodes of an open state switch is minimized.
It is another object of the invention to provide an electrical switch in which capacitance coupling between switch-open electrodes is minimized through a shunt grounding of the movable switch element in its open-switch condition.
It is another object of the invention to provide an integrated circuit-compatible micro electromechanical systems (MEMS) switch.
It is another object of the invention to provide a micro electromechanical systems (MEMS) switch of the micromachined electromechanical radio frequency type.
It is another object of the invention to provide a MEMS electrical switch having improved isolation, low electrical loss, high operating speed, low activation voltage and improved manufacturability.
It is another object of the invention to provide a MEMS electrical switch having decreased insertion loss and improved isolation at frequencies above 1 gigahertz in comparison with a comparable transistor or diode switch.
Additional objects and features of the invention will be understood from the following description and claims and the accompanying drawings.
These and other objects of the invention are achieved by the method of performing electrical switching in a metallic conductor signal path of a radio frequency integrated circuit electrical device, said method comprising the steps of:
interrupting a lengthwise extent of said signal path with a movable metallic conductor-inclusive electrical switching member having said movable metallic conductor selectably disposable by incorporated spring tension in one of an electrically open switching position and an electrically closed switching position;
changing said switching member movable metallic conductor switching position with electrostatic force generated by an electrical potential switch control signal;
limiting spring tension urged movable metallic conductor movement arc and switch element spacing gap of said movable metallic conductor electrical switching member with a metal stopping member selectively disposed along a switch position-changing swing path thereof;
coupling radio frequency electrical signal between said movable metallic conductor-inclusive electrical switching member and a switch output conductor member using increased electrical capacitance coupling achieved between said members in said electrically closed switching position;
limiting capacitance-accomplished electrical signal coupling between said movable metallic conductor electrical switching member and said switch output conductor member by grounding said movable metallic conductor electrical switching member to a grounded electrical potential metal stopping member in said switch electrically open position.